ANGIOGRAMS |
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An angiogram is a method to visualize the interior of an artery. A cardiac catheterization is method by which long, thin plastic tubes, called catheters, are inserted into a blood vessel in the leg or arm using a local anesthetic and then advanced under fluoroscopic guidance to the heart. Once they are in the heart, the catheters can measure the pressures within the chambers of the heart as well as how much blood the heart is actually pumping to the rest of the body. This lets doctors know how well the heart is working. It is also used to assess diseases of the heart valves as well as congenital heart disease.
However, the most common reason a cardiac catheterization is done is to perform a coronary angiogram, i.e. take a picture of the arteries that supply blood to the heart muscle. This is accomplished by injecting an X-ray dye that can be seen on X-ray film through the catheters into the coronary arteries. Blockages in these arteries is what causes angina and heart attacks. Rather than producing still pictures, an actual X-ray movie is made of the dye coursing through the arteries.
The only preparation for the procedure is that the patient should not eat or drink anything after midnight the night before. The patient's usual medications can be taken the morning of the test with a small sip of water. Some medicines may have to be stopped the day of or several days before the test such as the powerful blood thinner coumadin and diabetic medications.
The test is done in a room in a hospital called a cardiac catheterization lab. The patient lays on a table. A cylindrical camera is positioned over the chest. The physicians and nurses are usually standing to the right of the patient.
The test does not hurt and the patient is not put to sleep. However, they are generally given a medicine by mouth to relax them. The blood vessels that the catheters are placed in are usually those that lie right under the skin at the right groin, where the leg joins the abdomen. However, the left groin can also be used as well as either arm, just above the crook of elbow.
A local anesthetic is placed into the skin overlying the blood vessels. The patient will feel a needle stick and then some burning for a few seconds. When the catheters are first inserted into the blood vessel, the patient may feel a pressure there but no pain. The catheters are then advanced to the heart. There are no sensory nerves in the blood vessels so this is completely painless.
When the dye is injected, the patient will be asked to hold their breath for a few seconds. The camera makes a whirring noise for a few seconds as it takes the picture of the dye being injected into the artery. The patient then resumes breathing normally. Occasionally, the patient may be asked to cough after an injection.
Multiple pictures are taken from multiple angles. The camera is generally moved to a different position for each injection. Most injections don't produce any symptoms. However, there is one injection of dye into the main pumping chamber of the heart that results in a warm, flushed feeling all over for about 30 seconds as the dye washes through the patient's body. The entire procedure for a routine coronary angiogram takes about 20 to 30 minutes.
After the procedure, the catheters are removed. Stitches are not generally required. Pressure is simply applied to the puncture site to allow it close. If the procedure was done from the groin, the patient must then lay flat in bed without moving that leg for 6 hours. A nurse will assist them with eating and going to the bathroom. The dye makes people urinate quite a bit so it is important to drink a lot of water after the procedure is finished to avoid becoming dehydrated. After 6 six hours, the patient is allowed to get up and walk. If the test is done on an outpatient, they can go home once they are walking.
Someone else should drive the patient home and they should rest at home for the rest of the day. Unless instructed otherwise by the doctor, normal activities can resume the following day. The patient will feel back to normal by then.
Why are angiograms done? These are the most common reasons:
To make a definitive diagnosis of blocked arteries when other clinical information and tests are equivocal.
To determine if the blockages in the arteries are severe enough to be responsible for any symptoms the patient may be having.
To determine if a patient's blockages would be best treated by procedures such as an angioplasty or bypass surgery.
To assess the risk of future heart attacks in patients who have already had a heart attack or damage to their heart muscle.
Are there alternatives to angiograms? Not really. Stress tests help let doctors know if a person has blocked arteries or not and give some idea of their severity but they are not 100% accurate. Even the best stress tests, done in conjunction with echo or nuclear isotope pictures are only about 85% accurate. Computed tomography (CT) scans of the heart to detect coronary artery calcium share the same limitations. Neither of these tests can make a definitive diagnosis the way an angiogram can and neither of these tests can determine whether a patient needs an angioplasty or bypass.
There is a technique called Magnetic Resonance Angiography (MRA). This is an MRI scan that essentially produces an angiogram. It is quite useful for larger blood vessels such as the aorta and the arteries that go to the brain. It is not ready today for routine clinical study of the coronary arteries but rapid improvements in the technique hold promise for the future. Researchers are also studying whether or not Ultrafast CT scans can be used in place of angiograms to visualize the arteries of the heart. This technique is also rapidly improving with time and is now beginning to be incorporated into clinical practice.
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